Electric machine arrangement combining electromagnetic coupling with electric rotating machine

ABSTRACT

When an electromagnetic coupling is connected mechanically with an electric rotating machine having a stator, for instance a synchronous motor, a cage rotor type or wound rotor type induction motor etc., and the said electromagnetic coupling is connected electrically with the said electric rotating machine through a phase sequence change over switching device, further the electromagnetic coupling combined mechanically with the rotor of the electric rotating machine drives a load, and the other rotor of the electromagnetic coupling is driven by a driving machine, the electric machine arrangement has such advantages as shown by (1) obtaining power transmitting devices with operation similar to reduction gears which transmit outputs of other driving machines to loads; (2) possibility of driving one rotor of electromagnetic coupling in direction opposite to the rotation of the other rotor; and so forth. If the mechanical combination between the rotor of the electromagnetic coupling and the rotor of the electric rotating machine is made by using a rotor in common for the electromagnetic coupling and for the electric rotating machine, the electric machine arrangement becomes compact.

United States Patent Shibata I Aug. 8, 1972 Primary Examiner-Gene Z.Rubinson [57] ABSTRACT When an electromagnetic coupling is connected 2Inventor: Fukuo Shibata, 13 mechanically with an electric rotatingmachine having Nishinomiya, Hyogwprefecture a stator, for instance asynchronous motor, a cage jgpan rotor type or wound rotor type inductionmotor etc.,

and the said electromagnetic coupling is connected [22] Filed: July9,1970 electrically with the said electric rotating machine [21] App1 N0;53,413 through a phase sequence change over switching device, furtherthe electromagnetic coupling com- 0 bined mechanically with the rotor ofthe electric rotat- Foreign Appllcatlon Prlonty Data ing machine drivesa load, and the other rotor of the Sept. 27 1969 Japan ..44/77266electwmagnetic is drive" by a driving Jan. 1 1970 Japan ..45/202 machinethe electric machine arrangement has Such advantages as shown by (1)obtaining power trans- [52] Us Cl 318/205 290/30 318/200 mitting deviceswith operation similar to reduction 322/29 gears which transmit outputsof other driving [51] Int Cl "02p 7/36 machines to loads; (2)possibility of driving one rotor [58] Field 199 200 of electromagneticcoupling in direction opposite to 318/265 the rotation of the otherrotor; and so forth. If the mechanical combination between the rotor ofthe [56] References Cited electromagnetic couplingand the rotor of theelectric rotating machine is made by using a rotor in common TE ST ESATE TS for the electromagnetic coupling and for the electric 912 1442/1909 M 318/205 rotating machine, the electric machine arrangement avorbecomes com act.

1,983,896 12/1934 Bottscher ..318/205 p 3,165,635 l/l965 Moss et al..322/29 X 7 Claims, 14 Drawing Figures 3,441,822 4/1969 Shibata..318/197 I 3 LOAD DRIVING 7 MACHINE PATENTEDAU: 8 I972 SHEET 1 OF 6PHASE SEQUENCE CHANGE OVER SWITCHING DE VICE FIG! 7} /DRIVING I ELECTRICELECTROMAGNETIC ROTATING COUPL'NG MAC I H NE Io PHASE SEQUENCE CHANGEOVER SWITCH/M5 M Z DEVICE 9 I 3 \FREOUENCY T CONVERTER n I I2 LOA 0\ a 76 DRIVING MACHINE ELECT [C ELECTROMAGNET- ROTATI 1c COUPLING 1o MACHINEF I6. 3

9 I4 I Ac-ac. PHASE SEQUENCE CHANGE OVER oouvEnrER SWITCHING DEVICE 8 7e omvme LOAD/ MACHINE l INVENTOR ELECTROMAGNETIC @MMH:

COUPLING PATENTEDAUI; 8 I972 3.683.249

sum 2 or 6 L 7 my 8 v 6 -omw-e MACHINE 5 r 4 1 ELECTRIC ELE T ROTATINGI0 COUgUwG MACHiNE I ROTATING ELECTRIC MACHINQ mm 7 6 -o /vme I MACHINE4 ELECTROMAGNE- TIC COUPLING I O 0- 5 0L aka 3FREQUENCY 9 I6 CONVERTERL640 8 6 umvme MACHINE ELE crmc 5 ELEC R AGNETIC ROTATING fiOUPLIy"-INVENTOR MACHINE 13M PATENTEDAUB 31912 sum 3 [1F 6 8 7 I4 LOAD/ 2 3omvnvs ACHINE ELECTROMAGNETIC ELECTRIy COUPLING ROTATING MACHINE 32 I 3LOAD I 2 DRIVING a4 7 MACHINE 35- m Mm IN VE NTOR PATENTEDMIB 19128.683.249 SHEET I UF 6 "FREQUENCY 9 3 CONVERTER 0 PHASE SEQUENCE (ikINGEOVER SWITCH- DEVICE 5\ 1 4 a 7 s \DRIVING MAcI-IINE LOAD 2ELECTROMAGNETIC ELECTRIC OUPLING ROTATING MACHINE 16.10

RE UE CY 5ONI9ER E mm 4% ,6 O

DRIVING LOAD "'j MACH/NE ELECTROMAGNETIC COUPLING ELE ROTATING I MACHINEINV E N TOR P'A'IE'NTEDAUU 8 I912 3,683,249

SHEET 5 [1F 6 FIG. 1

/ a LECTRIC LOAD ROTATING 3 4 MACHINE I ELECTROMAGNETIC COUPLING F 162/2W 5; i7 F -o 0% 0 I7 O 9 5 W 2 v L :10

FREQUE Y CONVERTER a 7 \ELECTRIC ROTATING A? 4 MACHINE 3 I LOADELECTROMAGNETIC COUPLING I NVENTOR PATENTEDIUG 8 I972 SHEEI 6 [IF 6 FIG.I3

\C \F -o 20 I ELECTRIC 22 25 EL ROTATING MACHINE\ A. c. GENERATOR 26ELECTROMAGNETIC COUPLING If P I a 7 24 DIESEL LOAD 29 25 "DIESEL IELECTROMAGNETIC LOAD COUPLING ELECTRIC ROTATING ii MACHINE 4 F I 6 I4 29V T if E 4 ELECTROMAGNETIC cOuPLING 2 l INVENTOR ELEcTRIc ROTATING MWMACHINE COMBINING ELECTROMAGNETIC COUPLING WITH ELECTRIC ROTATINGMACHINE BACKGROUND OF THE INVENTION 1 Field of the Invention Thisinvention is used in fields in which it is necessary to transmit anoutput of a prime mover such as a diesel engine to a load such as apropeller of a ship, a wheel of a car, a fan, pump, etc. Of course, asteam turbine, a water wheel, an electric motor, a gas turbine, etc.other than the said diesel engine can also be used as the said primemover.

2. Description of the Prior Art In some prior arrangements in whichoutputs of prime movers are transmitted to loads, gears are used foraddition or reduction of speeds. In general, a gear itself controlneither the ratio of addition nor reduction of the speed, nor directionof rotation of a load. In other words, when only a gear is insertedbetween a prime mover and a load, the speed of the load cannot becontrolled or changed by the gear itself, and the direction of therotation of the load cannot be changed in the direction of the rotationof the prime mover is kept constant.

SUMMARY OF THE INVENTION It is primary object of the invention toprovide an arrangement transmitting an output of a prime mover or adriving machine to a load in which the load speed can be controlledeasily by the operation of a device provided in the arrangement itself.

Another object of the invention is to provide an arrangementtransmitting an output of a prime mover or a driving machine to a loadin which the direction of the rotation of the load can be changed whilstkeeping the direction of the rotation of the prime mover constant.

An additional object of this invention is to provide an arrangementcombining and transmitting a plurality of prime mover outputs to a loadin which the rotation of the load can be changed whilst keeping thedirection of the rotation of the prime movers constant.

A further object of this invention is to provide a control systemaffording wide speed ranges for an arrangement transmitting an output ofa prime mover or a driving machine to a load which shall be very simpleand efficient in operation and which may be readily and economicallymanufactured and installed.

A still further object of this invention is to make it possible toconstruct the said arrangements compactly.

A still more further object of this invention is to make it possible toreduce considerably a space of an engine room of a vessel whilst keepinga total output capacity of combined engines large.

Other objects of this invention will in part be obvious and in partappear hereinafter.

Accordingly, this invention is disclosed in the embodiments thereofshown in the accompanying drawings and comprises the features ofconstruction, combination of elements and arrangement of parts whichwill be indicated in the appended claims.

BRIEF DESCRIPTION OF THE DRAWING Referring to the drawing:

FIG. 1, FIG. 2, FIG. 3, FIG. 4, FIG. 5 and FIG. 7, illustratediagrammatically embodiments of this inventlon.

FIG. 6 illustrates one embodiment of construction used as a part of anarrangement of this invention.

FIG. 8 illustrates diagrammatically a part of an embodiment of thisinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1 and FIG. 6an electric machine arrangement of this invention has a combination of:an electromagnetic coupling 1 having two rotors 2, 3 which rotate withrespect to each other and one of which is provided with an armaturewinding; an electric rotating machine 7 having a stator, a rotor and anarmature winding, in which alternating current flows mechanicalcombination of one of the said two rotors 2, 3 of the saidelectromagnetic coupling 1 with the said rotor of the said electricrotating machine 7; and electric connection ll, 12 between the saidarmature winding of thesaid electromagnetic coupling 1 and the saidarmature winding of the said electric rotating machine 7 through a phasesequence change over switching device 9; wherein the rotor 2 of theelectromagnetic coupling 1 combined mechanically with the rotor of theelectric rotating machine 7 drives a load 8, and the other rotor 3 ofthe electromagnetic coupling 1 is driven by a driving machine 6,further, the said mechanical combination between the rotor of theelectromagnetic coupling 1 and the rotor of the electric rotatingmachine 7 is made by an arrangement of a rotor 2 which is provided withmaterial of a magnetic circuit for the electromagnetic coupling in itsinner face 41 and is provided with material of a magnetic circuit forthe electric rotating machine 7 in its outer face 42 and which rotatesin a space between the stator 36 of the electric rotating machine 7 andthe other rotor 3 of the electromagnetic coupling 1. Examples of thesaid electric rotating machine 7 are a synchronous machine, a cage rotorinduction machine, a wound rotor induction machine etc. In FIG. 1, arotor 2 is provided with an armature winding and sliprings 4; and arotor 3 is provided with a field winding and sliprings 5 which iselectrically connected with rectifiers 10 in order to be supplied withdirect current. In FIG. 1, the rotor 3 of the electromagnetic coupling 1combined mechanically with the rotor of the electric rotating machine 7drive a load 8, and the other rotor 2 of the electromagnetic coupling 1is driven by a driving machine 6. A propeller of a ship, a wheel of acar, a fan, a pump etc. are examples of the said load 8. Prime moverssuch as a diesel engine, a steam turbine, a water wheel, an electricmotor, a gas turbine etc. are examples of the said driving machine 6. InFIG. 1, it can be so arranged that the direction of rotation of therotor of the electric rotating machine 7 is opposite to the direction ofrotation of the rotor 2 of the electromagnetic coupling 1 driven by thedriving machine 6 through the electric connection of the phase sequencechange over switching device 9.

If the revolutions per minute of rotors 2 and 3 of the electromagneticcoupling 1 are respectively N and N and N N we can obtain where N, isrevolutions per minute of the rotor 2 in relation to the rotor 3.

positive. Whether the direction of the rotation of the rotor 3 may besame as that of the rotor 2 or not, the electromagnetic coupling actsnot only as a coupling but also as a generator.

In such a case, an electric machine arrangement combining anelectromagnetic coupling with an electric rotating machine 7 cantransmit an output of a driving machine 6 to a load 8, and further, thedirection of the rotation of the load 8 can be changed whilst keepingthe direction of the rotation of the driving machine 6 constant. It isvery important when the driving machine is a prime mover such as adiesel engine, a steam turbine, a gas turbine etc., and the load 8 is apropeller of a ship.

If numbers of poles of the electromagnetic coupling 1 and the electricrotating machine 7 are respectively p and p and frequency of alternatingcurrent flowing in the circuit between the electric rotating machine 7and the electromagnetic coupling 1 is f, we can obtain N,,= lf/p,

Therefore,

From Equations 1) and (4),

If p p the direction of rotation of the rotor of the electric rotatingmachine 7 can be opposite to the direction of rotation of the rotor ofthe electromagnetic coupling 1. If the electric rotating machine 7 haspole change windings, and the electric connection 11 is made between thearmature winding of the electromagnetic coupling 1 and the pole changearmature windings of the electric rotating machine 7 through the phasesequence change over switching device as shown in FIG. 8, therevolutions per minute of the load 8 when the direction of the rotor ofthe electric rotating machine 7 is opposite to that of the drivingmachine 6 can be decided to be favorable to the load 7 regardless of therevolutions per minute of the load 8 when the direction of the rotor ofthe electric rotating machine 7 is same as that of the driving machine6. Similar effect of operation of this invention as the above can beobtained when the electromagnetic coupling 1 has pole change windings,and the electric connection is made between the pole change armaturewindings of the electromagnetic coupling 1 and the armature winding ofthe electric rotating machine 7 through the phase sequence change overswitching device 9 as shown in FIG. 7.

As is understood from the above explanation, the construction of thisinvention made by the combination of the electromagnetic coupling 1 andthe electric rotating machine 7 can be operated as a device similar to areduction gear. The speed of the revolving shaft of the input rotor ofthe electromagnetic coupling 1 is reduced to the speed of the rotorshaft of the electromagnetic coupling 1. The construction of the priorelectromagnetic method such as the U.S. Pat. No. 912,144 can never beoperated as a device similar to a reduction gear. The operation of thisinvention similar to a reduction gear can be improved by a phasesequence change over switching device inserted in the circuit betweenthe armature winding of the electromagnetic coupling 1 and the armaturewinding of the electric rotating machine 7. In other words, thedirection of the rotation of the load 8 can be changed whilst keepingthe direction of the rotation of the prime mover or the driving machine6 constant. The operation similar to a reduction gear can be done alsowhen the direction of the rotation of the load 8 is opposite to thedirection of the rotation of the driving machine 6 in this invention.Such operation cannot be done by the prior method such as the U.S. Pat.No. 912,144.

The pole change is important when the direction or rotation of the rotorof the electric rotating machine 7 is turned to the opposite side to thedirection of rotation of the rotor of the electromagnetic coupling 1, asis explained before. For instance, if the revolution per minute of therotor 2 of the electromagnetic coupling 1 or of the driving machine 6 is400 rpm., numbers of poles of the electromagnetic coupling 1 and theelectric rotating machine 7 are respectively 4 and 8, the revolution perminute of the rotor 3 of the electromagnetic coupling 1 or of the load 8becomes 133.3 rpm. by the Equation (5) N (p /p l)N when the direction ofrotation of the load 8 is same as that of the driving machine 6. In thiscase, if the numbers of poles of the electromagnetic coupling 1 and theelectric rotating machine 7 are either respectively 4 and 16 orrespectively 2 and 8, when the direction of rotation of the load 8 isopposite to that of the driving machine 6, the revolution per minute ofthe rotor 3 of the electromagnetic coupling 1 or of the load 8 becomes133.3 rpm. by the Equation (5) N (p /p l)N Thus, the revolution perminute of the load 8 when the direction of rotation of the load 8 isopposite to that of the driving machine 6 can be same as that when thedirection of rotation of the load 8 is same as that of the drivingmachine 6 by using pole changing either of the electric rotating machine7 or of the electromagnetic coupling 1. Therefore, pole change isimportant in this invention.

In this invention, the mechanical combination can be made between therotor 2 of the electromagnetic coupling 1 and the rotor of the electricrotating machine 7 by an arrangement of a rotor which is provided withmaterial of a magnetic circuit for the electromagnetic coupling 1 in itsinner face 41 and is provided with material of a magnetic circuit forthe electric rotating machine 7 in its outer face 42 and which rotatesin a space between the stator 36 of the electric rotatingmachine 7 andthe other rotor 3 of the electromagnetic coupling 1, as shown in FIG. 6.

In FIG. 6, an inner face 44 of the magnetic circuit of the electricrotating machine 7 and an outer face 43 of the magnetic circuit of therotor 3 of the electromagnetic coupling 1 face each other through thefaces 41 and 42 of the rotor 2 of the electromagnetic coupling 1. Theelectric winding 32 of the rotor 3, the electric winding 33 of the rotor2 of the electromagnetic coupling 1, the electric rotor winding 34 ofthe electric rotating machine 7 and the electric stator winding 35 ofthe electric rotating machine 7 are shown in FIG. 6. Theseelectromagnetic coupling 1 and electric rotating machine 7 are coveredby a case 36. Symbols 37, 38, 39, and 40 show bearings.

In FIG. 2, a frequency converter 13 is connected electrically betweenthe armature winding of the electromagnetic coupling 1 and the armaturewinding of the electric rotating machine 7. FIG. 5 shows an embodimentof FIG. 2. In FIG. 5, the frequency converter 13 consists of diode typerectifier 17, a reactor 15 and controlled rectifiers 16. FIG. 7 showsthat the armature winding of the electromagnetic coupling 1 can beconnected electrically with an armature winding of an alternatingcurrent (A.C.) generator 22 driven by another driving machine 23. InFIG. 7, diesels 23, 24, 25 are shown as examples of driving machines.Electromagnetic couplings l and 31 provided with pole change windingsare shown, and symbols 26, 27 are change over switch for pole changingof electromagnetic couplings in FIG. 7. Electromagnetic couplings l and31 are connected electrically in parallel with the A.C. generator 20. Inthis case, two loads 8, 28, two electric rotating machines 7, and twochange over switching device 9, 29 are respectively shown in FIG. 7.

In FIG. 13, the direction of rotation of the rotor of the electricrotating machine 7 can be same as the direction of rotation of the rotorof the electromagnetic coupling 1 driven by the driving machine 24 byconnecting electrically the armature winding of the electric rotatingmachine 7 with one of the pole change armature windings of theelectromagnetic coupling 1 through the phase sequence change overswitching device 9, and the direction of rotation of the rotorof theelectric rotating machine 7 can be opposite to the direction of rotationof the rotor of the electromagnetic coupling 1 driven by the drivingmachine 24 by connecting electrically the armature winding of theelectric rotating machine 7 with the other of said pole change armaturewindings of the electromagnetic coupling 1 through the phase sequencechange over switching device 9. Symbols 20 and 21 are switches.

In FIG. 1 or FIG. 8, it can be so arranged that the direction ofrotation of the rotor of the electric rotating machine 7 is same as thedirection of rotation of the rotor of the electromagnetic coupling 1driven by the driving machine 6 by connecting electrically the armaturewinding of the electromagnetic coupling 1 with one of the pole changearmature windings of the electric rotating machine 7 through the phasesequence change over switching device 9, and the direction of rotationof the rotor of the electric rotating machine 7 is opposite to thedirection of rotation of the rotor of the electromagnetic coupling 1driven by the driving machine 6 by connecting electrically the armaturewinding of the electromagnetic coupling 1 with the other of the saidpole change armature windings of the electric rotating machine 7 throughthe phase sequence changeover switching device 9.

FIG. 3 and FIG. 4 are shown in order to illustrate the phase sequencechange over switching device 9 of FIG. 9 of FIG. 1. Further, it is alsoshown in FIG. 3 and FIG. 4 that the rotor provided with an armaturewinding of the electromagnetic coupling may be coupled mechanically byeither the driving machine 6 or the electric rotating machine 7.

What I claim is:

1. An electric machine arrangement which has a combination of:an'electromagnetic coupling having two rotors which rotate with respectto each other and one of which is provided with an armature winding; anelectric rotating machine having a stator, a rotor and an armaturewinding in which alternating current flows; mechanical combination ofone of the said two rotors of the said electromagnetic coupling with thesaid rotor of the said electric rotating machine; and electricconnection between the said armature winding of the said electromagneticcoupling and the said armature winding of the said electric rotatingmachine through a phase sequence change over switching device; whereinthe rotor of the electromagnetic coupling combined mechanically with therotor of the electric rotating machine drives a load, and the otherrotor of the electromagnetic coupling is driven by a driving machine,further,-the said mechanical combination between the rotor of theelectromagnetic coupling and the rotor of the electric rotating machineis made by an arrangement of a rotor which is provided with material ofa magnetic circuit for the electromagnetic coupling in its inner faceand is provided with material of a magnetic circuit for the electricrotating machine in its outer face and which rotates in a space betweenthe stator of the electric rotating machine and the other rotor of theelectromagnetic coupling.

2. An electric machine arrangement as claimed in claim 1, wherein theelectric rotating machine has pole change windings, and the electricconnection is made between the armature winding of the electromagneticcoupling and the pole change armature windings of the electric rotatingmachine through the phase sequence change over switching device.

3. An electric machine arrangement as claimed in claim .1, wherein theelectromagnetic coupling has pole change windings, and the electricconnection is made between the pole change armature windings of theelectromagnetic coupling and the armature winding of the electricrotating machine through the phase sequence change over switchingdevice.

4. An electric machine arrangement as claimed in claim 1, wherein afrequency converter is connected electrically between the armaturewinding of the electromagnetic coupling and the armature winding of theelectric rotating machine.

5. An electric machine arrangement as claimed in claim 1, wherein thearmature winding of the electromagnetic coupling can be connectedelectrically with an armature winding of an alternating currentgenerator driven by another driving machine.

6. An electric machine arrangement as claimed in claim 2, wherein thedirection of rotation of the rotor of the electric rotating machine canbe same as the direction of rotation of the rotor of the electromagneticcoupling driven by the driving machine by connecting electrically thearmature winding of the electromagnetic coupling with one of the polechange armature windings of the electric rotating machine through thephase sequence change over switching device, and the direction ofrotation of the rotor of the electric rotating machine can be oppositeto the direction of rotation of the rotor of the electromagneticcoupling driven by the driving machine by connecting electrically thearmature winding of the electromagnetic coupling with the other of thesaid pole change armature windings of the electric rotating machinethrough the phase sequence change over switching device.

7. An electric machine arrangement as claimed in claim 3, wherein thedirection of rotation of the rotor of the electric rotating machine canbe same as the direction of rotation of the rotor of the electromagneticcoupling driven by the driving machine by connecting electrically thearmature winding of the electric rotat-

1. An electric machine arrangement which has a combination of: anelectromagnetic coupling having two rotors which rotate with respect toeach other and one of which is provided with an armature winding; anelectric rotating machine having a stator, a rotor and an armaturewinding in which alternating current flows; mechanical combination ofone of the said two rotors of the said electromagnetic coupling with thesaid rotor of the said electric rotating machine; and electricconnection between the said armature winding of the said electromagneticcoupling and the said armature winding of the said electric rotatingmachine through a phase sequence change over switching device; whereinthe rotor of the electromagnetic coupling combined mechanically with therotor of the electric rotating machine drives a load, and the otherrotor of the electromagnetic coupling is driven by a driving machine,further, the said mechanical combination between the rotor of theelectromagnetic coupling and the rotor of the electric rotating machineis made by an arrangement of a rotor which is provided with material ofa magnetic circuit for the electromagnetic coupling in its inner faceand is provided with material of a magnetic circuit for the electricrotating machine in its outer face and which rotates in a space betweenthe stator of the electric rotating machine and the other rotor of theelectromagnetic coupling.
 2. An electric machine arrangement as claimedin claim 1, wherein the electric rotating machine has pole changewindings, and the electric connecTion is made between the armaturewinding of the electromagnetic coupling and the pole change armaturewindings of the electric rotating machine through the phase sequencechange over switching device.
 3. An electric machine arrangement asclaimed in claim 1, wherein the electromagnetic coupling has pole changewindings, and the electric connection is made between the pole changearmature windings of the electromagnetic coupling and the armaturewinding of the electric rotating machine through the phase sequencechange over switching device.
 4. An electric machine arrangement asclaimed in claim 1, wherein a frequency converter is connectedelectrically between the armature winding of the electromagneticcoupling and the armature winding of the electric rotating machine. 5.An electric machine arrangement as claimed in claim 1, wherein thearmature winding of the electromagnetic coupling can be connectedelectrically with an armature winding of an alternating currentgenerator driven by another driving machine.
 6. An electric machinearrangement as claimed in claim 2, wherein the direction of rotation ofthe rotor of the electric rotating machine can be same as the directionof rotation of the rotor of the electromagnetic coupling driven by thedriving machine by connecting electrically the armature winding of theelectromagnetic coupling with one of the pole change armature windingsof the electric rotating machine through the phase sequence change overswitching device, and the direction of rotation of the rotor of theelectric rotating machine can be opposite to the direction of rotationof the rotor of the electromagnetic coupling driven by the drivingmachine by connecting electrically the armature winding of theelectromagnetic coupling with the other of the said pole change armaturewindings of the electric rotating machine through the phase sequencechange over switching device.
 7. An electric machine arrangement asclaimed in claim 3, wherein the direction of rotation of the rotor ofthe electric rotating machine can be same as the direction of rotationof the rotor of the electromagnetic coupling driven by the drivingmachine by connecting electrically the armature winding of the electricrotating machine with one of the pole change armature windings of theelectromagnetic coupling through the phase sequence change overswitching device, and the direction of rotation of the rotor of theelectric rotating machine can be opposite to the direction of rotationof the rotor of the electromagnetic coupling driven by the drivingmachine by connecting electrically the armature winding of the electricrotating machine with the other of the said pole change armaturewindings of the electromagnetic coupling through the phase sequencechange over switching device.